The closure prohibits the launch or removal of any boat, dock or other structure from either reservoir that could potentially transport mussels, according to Mark Wolcott, the incident commander of the rapid response team created to address the issue.

The restrictions are needed to prevent the spread of aquatic mussels to other uncontaminated water bodies, Wolcott said. They will remain in effect until the reservoirs ice up.

The directors of the Montana Department of Natural Resources and Conservation and the state’s Department of Fish, Wildlife and Parks approved the boating restrictions, the Independent Record (bit.ly/2fYqOzL) reported.

The closure announcement came a day after Gov. Steve Bullock declared a natural resources emergency over the presence of the larvae of invasive aquatic mussels in the Tiber Reservoir. Further analysis is being done after suspected positive tests were obtained at Canyon Ferry Reservoir, the Milk River below Nelson Reservoir and the Missouri River near Toston.

Bullock’s declaration freed up $750,000 in state special funding to address the issue.

No adult mussels have been found so far. However, response team member Bryce Christiaens said officials are operating under the assumption that adults are present.

The team is contacting experts in other states to determine lowering reservoir levels could help control the spread of the mussels. Doing so would also would make it easier to search for adult mussels that might be left dry by receding water, officials said.